FUNGI 157 
gelatinous, dark-brown, shell-shaped masses, resembling 
ears; still others resemble fleshy branching corals (Fig. 151), 
and hence are called coral Fungi. 
In general, mushrooms are harmless and often useful 
saprophytes, but there are also destructive parasitic forms 
4 
if 
Fic. 150.—Mushroom with spine-like Fic. 151.—The common edible coral 
processes instead of gills.— After fungus.—After G1Bson. 
GIBSON. 
that attack forest-trees. The mycelium usually spreads 
between the bark and the wood, sending special absorbing 
branches into the wood, often even into the heart wood, 
causing decay and weakening of the stem. The spore- 
bearing structures are sent to the surface, and appear as 
toadstools, bracket Fungi, etc. Spores are produced in 
great profusion and infect other trees, the new mycelium 
using wounds to effect its entrance. Some mycelia spread 
through the soil, inoculating trees through their roots; while 
